Isle of Grain site for £50bn project is in middle of major flight paths for four London airports.

Nats chief Richard Deakin said the architects had not contacted the air traffic control service about its feasibility.

A proposed airport in the Thames estuary would be in the “very worst spot” for the south-east’s crowded airspace, according to the boss of Britain’s air traffic control service, Nats. Richard Deakin, chief executive of Nats, said the architects of the Thames Hub airport had not contacted them beforehand to discuss its feasibility. Norman Foster and partners unveiled the blueprints of the £50bn project last November.

London mayor Boris Johnson has championed the idea of a Thames estuary hub in response to a growing clamour in the aviation industry and business for more capacity. The government has indicated that a much-anticipated consultation on aviation this summer will look at all options for airports except a third Heathrow runway, although the launch has been delayed until after the mayoral elections.

Deakin said the proposed site for the new airport, on the Isle of Grain, was directly under the convergence of major arrival and departure flight paths for four of London’s five airports.

Pointing to the Thames estuary on a map, he said: “The very worst spot you could put an airport is just about here.”

He said there were “serious challenges” to integrate an airport into that traffic pattern, and added: “We’re a little surprised that none of the architects thought it worthwhile to have a little chat” with the air traffic controllers.

While Deakin conceded that “technically anything is possible”, he said that beyond the well-documented risk of strikes from the thousands of birds found in the wetlands, the proximity of Amsterdam’s Schiphol airport would also affect traffic patterns and force aircraft into more circuitous flight paths.

Such flight paths would run counter to much of the work being done to reduce fuel consumption in air travel. Industry bodies such as Sustainable Aviation say significant cuts in aircraft CO2 emissions could be made by planning more direct, intelligent flight paths.

He said that from an air traffic control point of view, “the single biggest thing we could do to reduce CO2 in the UK is to build a third runway at Heathrow”.

Deakin claimed that the extra runway could cut the need for aircraft to hold in the skies before landing. “Heathrow holding is not about airspace – it’s about lack of tarmac. I’m very confident you’d eliminate all the holding patterns in one go.”